Lawler Alyssa J, Duda Thomas F
Museum of Zoology and Department of Ecology and Evolutionary Biology, University of Michigan, 1109 Geddes Avenue, Ann Arbor, MI 48109, USA.
Museum of Zoology and Department of Ecology and Evolutionary Biology, University of Michigan, 1109 Geddes Avenue, Ann Arbor, MI 48109, USA; Smithsonian Tropical Research Institute, Balboa, Ancón, Panama.
Mol Phylogenet Evol. 2017 Apr;109:421-429. doi: 10.1016/j.ympev.2017.02.011. Epub 2017 Feb 17.
Knowledge concerning the taxonomic diversity of marine organisms is crucial for understanding processes associated with species diversification in geographic areas that are devoid of obvious barriers to dispersal. The marine gastropod family Conidae contains many species complexes due to lack of clear morphological distinctiveness and existence of morphological intergradations among described species. Conus flavidus Lamarck, 1810 and Conus frigidus Reeve, 1848 are currently recognized as distinct taxa, but are often difficult to distinguish by morphological characters and include several synonyms, including Conus peasei Brazier, 1877. C. peasei was originally described by Pease in 1861 (as Conus neglectus) based on slight morphological differences of a population of C. flavidus from Hawaii that distinguished it from C. flavidus from elsewhere. To evaluate the systematics of this group and specifically test the hypothesis of synonymy of C. peasei with C. flavidus, we examined molecular and morphometric data from specimens of C. flavidus, C. frigidus and C. peasei (i.e., C. flavidus from Hawaii). Multiple clades that contain individuals from particular geographic regions are apparent in gene trees constructed from sequences of a mitochondrial gene region. In particular, sequences of C. peasei cluster together separately from sequences of C. flavidus and C. frigidus. Although individuals of C. peasei, C. flavidus and C. frigidus each contain a unique set of alleles for a nuclear locus, a conotoxin gene, alleles of C. peasei are more similar to those of C. flavidus. In addition, sequences of a region of a second nuclear gene are identical among C. peasei and C. flavidus though they are distinct from sequences of C. frigidus. Morphometric data revealed that shells of C. peasei are distinct in some aspects, but are more similar to those of C. flavidus than to those of C. frigidus. Taken together, these results suggest that C. peasei represents a distinct species. Moreover, based on the contradictory relationships inferred from the mitochondrial and nuclear sequences (as well as morphometric data), C. peasei may have originated through past hybridization among the ancestral lineages that gave rise to C. flavidus and C. frigidus.
了解海洋生物的分类多样性对于理解在没有明显扩散障碍的地理区域中与物种多样化相关的过程至关重要。由于缺乏明确的形态特征以及已描述物种之间存在形态渐变，海洋腹足纲芋螺科包含许多物种复合体。1810年拉马克描述的淡黄芋螺（Conus flavidus）和1848年里夫描述的冷芋螺（Conus frigidus）目前被认为是不同的分类单元，但通常很难通过形态特征区分，并且包括几个同物异名，其中包括1877年布雷齐尔描述的皮氏芋螺（Conus peasei）。皮氏芋螺最初由皮斯于1861年（当时名为疏忽芋螺（Conus neglectus））根据来自夏威夷的一群淡黄芋螺的轻微形态差异进行描述，这些差异使其与其他地方的淡黄芋螺区分开来。为了评估该类群的系统分类，并特别检验皮氏芋螺与淡黄芋螺同物异名的假设，我们检查了淡黄芋螺、冷芋螺和皮氏芋螺（即来自夏威夷的淡黄芋螺）标本的分子和形态测量数据。从线粒体基因区域序列构建的基因树中可以明显看出，包含来自特定地理区域个体的多个分支。特别是，皮氏芋螺的序列与淡黄芋螺和冷芋螺的序列分开聚类。尽管皮氏芋螺、淡黄芋螺和冷芋螺的个体各自包含一组独特的核基因座等位基因，即一种芋螺毒素基因，但皮氏芋螺的等位基因与淡黄芋螺的等位基因更相似。此外，第二个核基因区域的序列在皮氏芋螺和淡黄芋螺之间是相同的，尽管它们与冷芋螺的序列不同。形态测量数据显示，皮氏芋螺的贝壳在某些方面是独特的，但与淡黄芋螺的贝壳比与冷芋螺的贝壳更相似。综合来看这些结果表明皮氏芋螺代表一个独特的物种。此外，基于从线粒体和核序列（以及形态测量数据）推断出的矛盾关系，皮氏芋螺可能是通过产生淡黄芋螺和冷芋螺的祖先谱系之间过去的杂交而起源的。
